Hi Jakobberry, The reason for the 551 is simply to keep this project as small as possible using a AAA battery as the power source. You can use a 555 without any other changes but of course you must use a different power source.

I use Cinema 4d for all my 3d modeling and animation. It is the easiest to learn and the most intuitive. Take a look at the Cinema website and download a demo, then go to my 3d blog and download lots of models for free, then simply play with Cinema 4d. Have fun

i got to tell ya, this is the first time i have commented on anything here, you put a lot of work into this, and it shows.... i need to get back into doing stuff like this... you did a great job, i need to get into this.... i need a solar powered led project.... just 2 lights to light the stairs, got any ideas?